Joaquin Phoenix reportedly “storm­ed out” before a Las Vegas concert after losing his cool with a film crew, femalefirst.co.uk reports.

The actor-turned-singer is believed to have been furious when Casey Affleck’s camera crew — who are documenting Joaquin’s transition into music — were late for his sound check at LAVO nightclub last week, the website adds.

A source said: “He was waiting for Casey Affleck and when the film crew arrived late, Joaquin flipped out. Phoenix yelled at the crew, ‘Thanks for being late and f—ing everything up.’ He then threw a CD on the floor and stormed out.”

Phoenix soon regained his composure and returned to the stage to rehearse his set, leaving onlookers unsure if he was genuinely annoyed.

The source added to the New York Post newspaper: “He came back five minutes later and did the sound check. Nobody can tell if he is for real or if this is all a big joke.”

Later that night, the 34-year-old star surprised onlookers by performing three hip-hop numbers.

During his set, a dishevelled Joaquin — who was sporting an unkempt beard and long hair — danced unsteadily and fell into the crowd as he exited the stage, adds the website.